Standards void slows modems

"This is on the fast track for the committee," said Susan Hoyer, manager of
technology and regulatory affairs for TIA.


Even so, temporary ground rules for interoperability of the new modems and servers
aren't likely to be in place before late 1997, Hoyer said.


The scramble to define standards underscores other concerns about competing units now
coming into the market. At present, the modem chip set from Lucent Technologies/Rockwell
Semiconductor and the one from U.S. Robotics cannot talk to each other, and neither is
likely to deliver true transmission speeds of 56 kilobits/sec.


In January, Lucent Technologies Inc. of Murray Hill, N.J., proposed elements of its
design to the TIA engineering subcommittee as a standard. TIA's interim standards
eventually could be submitted to the American National Standards Institute for national
certification.


U.S. Robotics Inc. of Skokie, Ill., submitted its proposed standard directly to the
International Telecommunications Union. ITU's international standards could take several
years to formulate.


This lack of standards worries vendors as well as users of the new modems.


"The only reason we started touting it is because our competition started touting
it," said Jim Stacklie, regional sales manager for Multi-Tech Systems Inc. of Mounds
View, Minn. "It's going to be mass confusion out there for the rest of the
year."


Stacklie and product marketing manager Paul Kraska seemed less than enthusiastic about
Multi-Tech's announcement of a line of 56-kilobit/sec modems and servers using the
Lucent/Rockwell chip set.


"We'll have 56K capacity shipping this year, but the standards won't be
there," Kraska said. "56K has great potential. It's too bad it's being
introduced with a lot of hype."


The federal government is a significant market for Multi-Tech products, but Stacklie
said he has no plans to promote the fast modems to feds until the technology stabilizes.
Agencies so far have been cool toward the new devices.


"I'm sure it will have a pretty big impact eventually, but I haven't seen any
requests for quotations for it yet," Stacklie said.


John Culberson, head of the General Services Administration's local networking and
end-user support center, said most of GSA's connections are at 28.8 kilobits/sec, and he
has nothing faster than 33.6 kilobits/sec. The availability and limitations of
56-kilobit/sec modems aren't yet an issue at GSA, he said.


The new modems rely on the increasingly digital public switched telephone network for
top speeds. Like other modems, they convert a computer's digital signal into an analog
signal for transmission over local phone lines.


More than likely, the telephone carrier's central office then converts that signal back

to digital for transmission across upgraded portions of its network.


If the signal can travel directly over digital lines to a compatible server without
having to be reconverted again to analog, transmission is significantly faster.


But there are limits. If a second digital-to-analog conversion takes place at the other
end of the circuit, transmission rates drop, and two computers communicating with the same
brand of 56-kilobit/sec modem couldn't talk any faster than the current ITU V.34 standard
of 33.6 kilobits/sec. The higher speed also is lost if the server and modem employ
different 56K chip sets.


Poor-quality telephone connections also reduce performance of the high-speed modems.
And even when everything is working correctly, the user gets 56 kilobits/sec only when
downloading from the server.


Uploading requires the telephone company to convert an analog signal to digital,
introducing noise and slowing transmission to 45 kilobits/sec or less.


The asymmetry in these maximum speeds means the new modems are best suited for Internet
connections, where the bulk of data flow is downstream.


Despite these drawbacks, the new modems have great potential, Multi-Tech president
Raghu Sharma said. "If a sustained rate of 45 or 55 kilobits/sec can be achieved for
typical calls, this will advance data communications performance more than any other modem
technology in recent years," he said.


The company's new MultiModem ZDX desktop modem for PC serial ports, the MultiModem ZPX
internal modem and the internal plug-and-play MultiModem ZPW for Microsoft Windows 95
initially will come with V.34 capability and will be upgradeable to 56-kilobit/sec
capability.


Multi-Tech's Kraska couldn't say exactly when the new user-end devices will be
available.


About the Author

William Jackson is a Maryland-based freelance writer.

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